One conventional device for cleaning a submerged surface (such as the bottom of a swimming pool filled with water) is designed to move randomly along the submerged surface. One such device is described in U.S. Pat. No. 4,521,933, issued Jun. 11, 1985 to Raubenheimer. The Raubenheimer device is designed for connection, by a flexible tube, to a suction apparatus disposed on the surface. While the surface apparatus pumps a stream of water up through the tube, a turbine within the bottom device is caused to rotate by the flowing stream. The rotating turbine, in turn, actuates components which cause the device to "walk" on the submerged surface on pivoting feet composed of a thermoplastic elastomer. A second turbine assembly causes the device to turn (from time to time) in a randomly-determined direction.